RESUMEN
Limited by the narrow enhanced area of nanoscale on the metal surface, the sensitivity of surface-enhanced Raman spectroscopy (SERS) detection in solution is usually much lower than the detection in a solid substrate, which is dramatic in microfluidics for online detection. In this work, a cellulose microfilament embraced by Ag nanoparticles, called plasmonic cellulose microfilament, is located in a microchannel for SERS detection in microfluidics. Benefiting from the congestion caused by the plasmonic cellulose microfilament in a microchannel, the trace molecule in the solution is much easier to gather in Ag nanoparticles for Raman enhancement. To obtain high sensitivity, the structure of plasmonic cellulose microfilament is optimized. The SERS spectra collected in this novel microfluidics demonstrate that the plasmonic cellulose microfilament presents a high sensitivity at 10-13 M and good reproducibility in SERS detection. In addition, automatic identification of urea presence or absence was achieved based on deep learning (DL) here. The results show excellent diagnostic accuracy (99 %), which suggests that a fast, label-free urea screening tool can be developed. These results point out this SERS microfluidics with plasmonic cellulose microfilament has a great application prospective in online SERS detection with high sensitivity.
RESUMEN
Optoplasmonic hybrid structures composed of photonic and plasmonic elements with excellent optical properties are of great significance for the development of surface-enhanced Raman spectroscopy (SERS) substrates. In this work, the optoplasmonic hybrid structure is composed of SiO2 microsphere and two-dimensional (2D) plasmonic- metal organic frameworks (MOF) film. Among them, the 2D plasmonic-MOF film is prepared from silver nanoparticles encapsulated by zeolitic imidazole acid framework (AgNP@ZIF-8) by self-assembly method. This optoplasmonic hybrid structure with gas adsorption properties could be used as a SERS substrate for 4-Mercaptophenol (4-MP) gas detection. Experimental data show that this substrate is dependent on the thickness of the ZIF shell and the size of the SiO2 microspheres. In addition, it is confirmed by the electromagnetic field simulation of finite-difference time-domain method (FDTD). The optoplasmonic hybrid microstructures exhibit good uniformity for detection of 4-MP gas molecules. This work not only broadens the understanding of our optoplasmonic hybrid structure, but also has broad application prospects in SERS and gas sensing related fields.